When North Korea launched a missile that flew over Japan last Friday morning, prompting authorities to broadcast an alert on cellphones and television, many people wondered: why didn’t the Japanese military shoot it down?
The government quickly judged that the missile was not targeting Japan, and it landed in the Pacific Ocean, about 1,370 miles east of Hokkaido, Japan’s northernmost island.
But officials in Japan who may have considered intercepting the missile faced two immediate constraints — the country’s missile defences are limited, and the constitution limits military action only to instances of self-defence.
Those same constraints have weighed heavily on the debate in recent weeks over how Japan should be responding to North Korea’s rapidly advancing nuclear programme, including what role it should play as a US ally and to what extent it should upgrade its armed forces.
Though Japan provided rear support for the US during the Vietnam and Korean Wars, its alliance with America has never been tested as it would be in a conflict with North Korea.
Any military action by the Trump administration against North Korea risks a retaliatory missile attack on Japan, where 54,000 US troops are based. Last week, North Korea threatened to “sink” Japanese islands with nuclear weapons, adding that “Japan is no longer needed to exist near us.”
Japan’s position east of North Korea also means that missiles fired by Pyongyang toward the US, including Guam, almost certainly would have to fly over Japanese territory. But the missile defence systems stationed across Japan on mobile launchers are designed only to intercept missiles as they are descending, not in midflight as they are headed to the United States. Other defence systems on four naval destroyers can target missiles midflight, but they have to be in the right place at the right time.
It is also unclear whether the pacifist constitution allows Japan to shoot down a missile headed for the US, much less initiate a pre-emptive attack on a missile on a launchpad in North Korea, as some in Japan believe it should be prepared to do.
In recent months, the government of Prime Minister Shinzo Abe has revived a long-simmering discussion over whether to acquire cruise missiles — which can be fired from land, air or sea — that would allow it to strike a launch site in North Korea if it detected signs of an imminent attack.
The Japanese government ruled in 1956 that such a pre-emptive strike fell under its right of self-defence, but some lawmakers say deploying cruise missiles could cross a line and break with longstanding policy established after World War II to eschew offensive weapons. While the Japanese public is anxious about North Korea, it is torn about developing the nation’s military capabilities.
“The Japanese public is still not so sure about this,” said Richard Samuels, the director of the Centre for International Studies at the Massachusetts Institute of Technology.
Bolster arms spending
US President Donald Trump signalled this month that he wanted Japan, along with South Korea, to bolster arms spending. In a Twitter post two days after North Korea conducted its sixth nuclear test, Trump said he would allow the two countries to “buy a substantially increased amount of highly sophisticated military equipment from the United States.”
It is unclear whether Trump had specific equipment in mind, or whether that included cruise missiles.
In Japan, part of the political calculation is how China or South Korea might react to such a purchase. “It will be an excuse to China for further military buildup,” said Koji Murata, a professor of international relations at Doshisha University in Kyoto. “And even in South Korea, some kind of anti-Japanese sentiment will be further facilitated.”
Itsunori Onodera, Japan’s defence minister, has avoided discussing a pre-emptive strike on North Korea. Instead, he speaks of counterstrikes, suggesting a more passive interpretation of the country’s legal rights under the constitution. “In Japan’s case, I don’t think we can shoot before we are shot,” said Noboru Yamaguchi, a professor of international relations at the International University of Japan in Niigata and a retired lieutenant general in Japan’s army, known as the Ground Self-defence Force. “Most likely, once we are shot and the second or third missiles are coming and they are on the ground, we can shoot back.”
Some analysts say that officials in Abe’s administration have been careful to use language that will not alarm the public. In polls, about half those surveyed say they would oppose Japan acquiring missiles to be used in pre-emptive strikes.
But as North Korea steps up missile launches and nuclear tests, Abe and his Cabinet can make a stronger argument for such missiles. “They can say ‘Look at what North Korea is doing. Yes, we have to protect ourselves,’” said Jeffrey W Hornung, a political scientist at the RAND Corp.
An upgrade of the country’s ballistic missile defences would be a much easier sell politically. To best protect itself from a missile attack, some experts say, Japan should buy a Terminal High Altitude Area Defence system, or THAAD, which intercepts enemy rockets at higher altitudes than its current land-based systems.
The US recently completed deploying THAAD in South Korea over vociferous protests from China, which has retaliated against Seoul by punishing it economically. That response has given some in Japan pause.
Instead, Japan has said it plans to equip and deploy more destroyers with the Aegis missile defence system. The defence ministry has also indicated it wants to acquire a land-based system, known as Aegis Ashore, which can intercept missiles above the atmosphere and above THAAD’s range.
Although the defence ministry recently increased its annual budget request to a record high of about $48 billion, its military spending relative to gross domestic product is minimal compared with that of other countries. And Japan may have other military equipment on its wish list, including amphibious vehicles or more fighter jets. “If the resources are limited, we have to prioritize,” Yamaguchi said. “North Korea is not the only problem. We have to deal with global terrorism, and we need to deal constructively with China,” he added, referring to Beijing’s territorial incursions in the East and South China Seas.